Cleaning Your Gas Blow Back

You’ve finished an all day skirmish in the rain and mud. You’re caked in dirt and filth. You’re gear looks like you just walked out of the apocalypse. You throw your BDU’s in the wash, knock the dirt off your gear (as we all know it’s not mil-sim to have clean gucci gear 😉 ), but that gas blowback is crying out for a good cleaning! Before you get yourself cleaned up, let’s get that gun shining new again.

Every gun is a bit different, so you might need to adjust what you see here to fit your gun. There are a few rules to cleaning a GBB that you should know before you begin:

  1. Too much lube is NEVER a good thing.
  2. You’ve got to get the dirt off before applying lube.
  3. Too much lube is NEVER a good thing.
  4. Always use silicone lube meant for airsoft or r/c cars.  NEVER use WD-40 as it will destroy any rubber seals it comes in contact with, and will mess up the plastic parts of your gun.
  5. Too much lube is NEVER a good thing.
  6. Make sure your gun is UNLOADED and double check the chamber is clear.

Items needed:

  • Silicon oil (the type used for airsoft or r/c cars)
  • Cotton Swabs
  • Cotton Towel
  • Gun Cleaning Patches (or if you don’t have these medical gauze works well also)
  • Inner Barrel Cleaning Rod

USP Field StrippedOkay with that out of the way let’s get to work. First things first, remove the mag and check to ensure that the chamber is clear then begin to field strip your gun. Every make and model is a bit different, but usually it involved pushing the slide back and manipulating the slide release and then pushing the slide forward. Remove the recoil spring, and then remove the barrel assembly. With that out of the way we can begin to clean it.

I would start by taking a towel and removing all the dirt I could with it. Starting with the slide (making sure to get the groves for the slide rail, and around the blow back mechanism). Then wipe down the outer barrel, then the recoil spring guide and spring. Then I would take the towel and run it through the mag well, making sure not to get it hung up on the mag release. Wipe down the frame paying attention to the hammer assembly.

wipe magwellWiping down the frameWiping Spring Guide

Clean GrooveWith the initial wipe down complete, let’s get in all the tight spots. Start with a cotton swab and run it through the grove in the slide where the slide rails contact. You might find that you’ll need several cotton swabs to get this clean. Keep doing this till there is little to no residue coming off of it. If it seems like it’s never ending, then spray a bit of the silicon lube on there and go at it again (that might loosen the dirt up). Now let’s use the swab around the gas blow back mechanism being careful not to allow any bits of the swab to get left behind in it. Clean the contact plate for the hammer and around the opening for the barrel.

Cleaning GBB Frame RailsNow let’s look at the body of the gun. Using the cotton swabs again, clean around the slide rails. Make sure these are very clean as this will affect the speed at which your gun will cycle. Then clean around the hammer assembly and make sure to look at all points that contact the slide. You’ll see wear points where parts move, and where the slide rubs the frame. Make sure each of these spots are cleaned throughly. Again, you might need to use several swabs to accomplish this.

Now clean the recoil spring guide and recoil spring. This does not need to be scrubbed, but just lightly wiped down. Push the spring back and wipe down the spring guide.

wipeing the outer barrelCleaning the barrel can be tricky and should be done with care. Take a cleaning rod meant for airsoft and check it to make sure it is straight and does not have any plastic burrs sticking out of it. Turn your hop up all the way down. Place a cleaning patch or some gauze in the patch holder. Spray it with some light silicone lube. Then twist the patch / gauze round the end of the cleaning rod before inserting it into the barrel. Push the cleaning rod in from the exit end of your barrel (not the hop up end) and twist it as you do. Run it back and forth in the barrel making sure not to touch the hop up with it at all. Always be careful not to get lube on the hop up and not to hit the hop up with the cleaning rod as it might damage it. Now pull out the cleaning rod and check to see if the swatch is dirty. If so, put a clean one on it again, lube it up, and run it in the gun again. Check to see if it comes out dirty. If so do it one more time. Then put a clean swab on the rod and run it through the gun till it comes out dry. Now look down the barrel (it is still out of the gun), and look to see if there is any dirt you missed. It should look shiny and smooth. Look for any dirt or grooves. Grooves are a sign of using bad bb’s or having a dirty barrel and using it anyway. This will reduce performance and increase the likely hood of jams.

silicone oilWith everything clean, it’s time to lube it up. Now I might have said this before, but too much lube is NEVER a good thing! Too much lube WILL attract dirt, and will make your gun sluggish and will work it’s way into the hop up and blow back chamber and wear out your gun faster. The proper lube to use for most of your gun might have came with it (as it did with my KWA USP .45), if not you can head to a hobby store and pick up a bit of silicone oil. You don’t want a watery oil, as you want it to stay where you put it.

First take your recoil spring guide and push the spring back. Put the tiniest drop (maybe 1/8″ in diameter) on it. Rub it around with your finger to coat.

Then apply just a drop or two (same size as before) on the outer barrel. Rub it around to coat with your finger. Make sure to put a touch of lube wherever you see wear marks as this is where the slide is contacting it.

Lube Outer Barrel

Lubing Frame RailsLooking at the hammer mechanism put a tiny drop on the moving portion on it and work it back and forth a bit. Look at the wear spots and moving points on the frame and put just a tiny bit of lube on them and then wipe it off lightly so as to leave a nearly non-existent coat of lube. Now take the frame and put the smallest drop you can on your slide rail. Now different guns are different so I’ll give you an idea of what to do here. If you have a few small contact points for your slide rail (as I do), then a tiny tiny drop on each one will suffice. If you have a continuous rail or a long rail, you might need two or so drops of it on one end and in the middle of the rail. Now set it aside (making sure not to wipe off the lube you put on). Now if you see that the oil you put on is running you’ve either put too much or it’s too thin and you should get a heavier weight.

Now grab the slide. Take a look at the blow back mechanism. It should slide back and forth easily. I would not worry about lubing this unless you see that it is not moving well. If it needs to be lubed, use a light weight spray lube (again, 100% silicone) and extremely lightly spray a touch.

One thing I like to do is take the spring and follower out of my mags, then apply a very tiny drop of light silicone lube at the top and bottom of the mag where the bb’s feed, then put the follower and spring back in (do this once every 6 months or every few serious skirmishes) . This will make loading the mag and moving the bb’s into the chamber easier. Again, be careful not to use too much lube.

Now put your gun back together and rack the slide several times (without a mag in the gun). Dry fire it a few times without the mag in it to cycle all the oil around. Then load up a few rounds into a mag and fire it one shot at a time (not rapidly cycling it). After you’re done, take the mag out and clear the chamber. Look to see if there is any blow-by (lube that is seeping out of the slide at the back of it, around the blowback mechanism, or around the rear sights (if they screw on above the blowback mechanism). If you do see some, take a swab and clean it up. That means you used too much lube, next time use less.

If you needed to clean up extra lube fire it a few more times (with bb’s in it), clear the chamber and mag well and check for more blow-by. And now you’re done!

Clean Gun


tags: airsoft technical clean gbb gun


2 responses

10 01 2013
Scott Helka

Hello to whom this may concern.. a friend and myself are venturing into a new company for airsoft . We have decided to switch from the green gast to silicon and propane… But what we want to do is get away from the small canisters and may be given an idea on how to go large. Propane will be easy to obtain and much cheaper plus it holds the fps much longer. we belive this mixture can be prepared in larger amounts. But how just how is my ? If you can help please email me at and thank you for any ideas

6 02 2013

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